This invention relates to an electrostatographic printer or copier, and more particularly concerns a diagnostic procedure to identify cleaner retraction timing faults.
Cleaning systems consist in large part of two general types of cleaners. For low volume applications, blade cleaners are frequently used due to their low cost. For high volume applications, brush cleaners, either mechanical or biased electrostatic, are frequently used due to their reliability and life. In multi-pass color xerographic systems, retraction of these cleaners, from the photoreceptor, is required while the color images are being developed.
These cleaners (e.g. brushes and blades) rely on mechanical mechanisms such as cams, linkages or slides to move the cleaning elements into and out of contact with the photoreceptor. The operating force for these mechanisms is normally supplied by electric motors and gear trains or is solenoids. These mechanisms or devices can fail due to breakage or binding causing the cleaning elements to remain in either a retracted or engaged position until repaired. The failure of these mechanisms can also cause the speed of the retraction and engagement motions to be reduced as a result of added frictional drag in the bearings, sliders, cams or seals due to contamination by toner, dirt or other debris.
Furthermore, contamination can cause a change in the actuation speed generated by the electromechanical drive components. An example of this change in actuation speed, includes over heating a solenoid or motor which changes the force or torque output of the device or mechanism. Failures due to reduced actuation speed are more difficult to diagnose than failures that stop the cleaning elements completely.
The following disclosure may be relevant to various aspects of the present invention and may be briefly summarized as follows:
U.S. Pat. No. 4,977,437 to Asai et al. discloses an image recording apparatus for recording an image of an original on a developer sheet with the use of a microcapsule, in which the developer sheet and the microcapsule sheet having a surface coated with immense number of photosensitive and pressure-rupturable microcapsules are subjected to pressure development by a pair of pressurizing rollers. To ensure that the pressure development is performed under the condition where the developer sheet and the microcapsule sheet are superposed one on the other, the nip and retract timings of the pressurizing rollers are determined properly according to the present invention. For example, the developer sheet is conveyed at a speed asynchronous with the microcapsule conveying speed and the conveyance of the developer sheet is stopped after its leading edge is introduced between the rollers held in spaced apart condition. The rollers are brought to the nip position to thereby start the pressure development when the exposure start line on the microcapsule sheet is in alignment with the leading end of the developer sheet. The retract timing is determined, for example, depending upon the size of the developer sheet.